The basic architecture, signal flow, and neurochemistry of signaling through the vertebrate retina is well-understood: photoreceptors, bipolar cells (BCs), and ganglion cells (GCs) are all thought to be glutamatergic neurons and the fundamental synaptic chain that serves vision is photoreceptor…
1 Vision from starlight to sunlight The human visual system operates effectively over an enormously wide range of intensities, of at least a billion-fold, from around 10 −4 cd m −2 under starlight conditions to around 10 5 cd m −2 under…
Retinal rods and cones are highly specialized neurons that respond to light with an electrical signal (see Chapter 18 ) and provide the sensory input for vision. In contrast to most other neurons, rods and cones maintain a relatively depolarized…
Overview Phototransduction is the series of biochemical events that lead from photon capture by a photoreceptor cell to its hyperpolarization and slowing of neurotransmitter release at the synapse. This overall process includes an activation phase and a recovery phase. While…
Introduction In ocular therapeutics, the current literature describes drug delivery limitations posed by outward directed transport mechanisms of the eye. Drug delivery to ocular tissues is restricted by various factors such as limited tissue penetration, rapid clearance rate, and dose-limiting…
Introduction The sensory innervation of the eye is provided by the peripheral axons of primary sensory neurons located in the trigeminal ganglion. The sensory nerves enter the eyeball mainly through the ciliary nerves and reach all ocular tissues with the…
1 Tear film overview The tear film overlays the ocular surface, which is comprised of the corneal and conjunctival epithelia, and provides the interface between these epithelia and the external environment. The tear film is essential for the health and…
Introduction The cranium protects the brain and provides scaffolding for facial structures. During primate evolution, the orbits were enlarged and reoriented towards the front of the face. This, along with the gradual flattening of the face, allowed for improved binocular…
Introduction The retinal pigment epithelium (RPE) is a monolayer of pigmented cells located between the light-sensitive photoreceptor outer segments and the fenestrated endothelium of the choriocapillaris. On both sides, specialized extracellular matrices enable a close interaction of the RPE with…
Introduction The vasculature of both the retina and brain can autoregulate, meaning that blood flow is altered in response to neuronal activity. This tight coupling between neuronal activity and blood flow, or neurovascular coupling, was first described in the brain…